The default format definition for a text input parameter for a date fields is not applied in Report Designer 3.8.
This is working in 3.6.
Attached is a sample report.
Open the report in 3.8 and do a preview.
The text input field does not match that defined in the default format.
Open the same report in 3.6 and do preview.
The date display matches that defined in the default format.
A video recording of the problem from the client is also attached.